Discharge tube with plated electrode



Oct. 11, 1949. F. PRAKKE ETAL 2,484,311

DISCHARGE TUBE WITH PLATED ELECTRODE Filed Aug. 8, 1946 IRON . VENTOFIPIT'S f ly/VOTE W/LLEM IIEE/WAN FLA/43 I? ENHU/ ATTORNEY.

Patented Oct. 11, 1949 ihui's; Eindhoven'; Netherlands, assignors toHartford National Bank and Trust -Company,

UNITED STATE Hartford, (Joni-mas trustee Application August 8, 1946,Serial No. 689,1I8 In the Netherlands August 27, 1943 Section 1, PublicLaw 690, August 8, 1946 Patent expires August 27, 1963 2 Claims. 1 Thisinvention relates to an electric discharge tube and more in particularto the constitution of the electrodes or other conductive members ofsuch a tube, such as, for example, anodes, screens,

2 the difference in depth of penetration of the electric current atlarger and at smaller wavelengths is made available. This depth ofpenetration is, for instance for copper, at a wavelength of 3 or thelike, 5 meters about 6.5 microns; thus, if a layer of from It is commonpractice to make such tube parts 15 to 30 microns is used, electrodes ofthis kind of nickel, iron, nickel-plated iron, aluminium have very goodskin effect properties for use even plated iron and similar materials.Now, if elecon very short Waves of decimeter and centimeter trodesconstructed in this manner are to be used length, Whilst at the sametime y have highly in discharge tubes for short and very short waves,satisfactory properties in Connection w h hi hfor example of less than 3meters, difliculties occur frequency deprival of gases, since at thewavedue to the fact thatthe losses owing to the skinlengths of from 50to 1000 meters then used the effect become too high. The resistance dueto ep h of penetration is considerably greater. so this effect is, forexample, represented by the that the electrodes are also deprived ofgases in fgrmulg, =K /Ij i which 3 i th specific a highly satisfactorymanner. Accordingly, a sistance, c the permeability, f the frequency andtube according to the invention is suitable above K a n ta t, hfrequency being given it i all tubes for use on short and very shortwaves. necessary, in order to minimize the resistance It of course,essentially p s l o us difl ss s, t ch te i l having a minimum feringsubstances both for the core material and m bi it t t, i t saynon-magnetic t '20 for the outer layer. Acombination of anickel corerial and consequently not nickel or iron, and to and a thin Outer layerof p f a pl ha use material having a minimum specific resist- Veryfavourable p p It s, however, also anee, In t respect t l h copper andpossible to use other, well-known electrode matesil e a very favourable,rials, such as iron or the like, and to coat them It i h e r impossiblet 1 i; i genera] '23 with a film of copper or of other material Whose tomake electrodes from copper or silver as these Conductivity is p o a e yof the same order materials, particularly silver, are mechanically ofmagnitude a that Of C pp insufliciently resistant; in addition, they arevery In Order that the invention y be cleiii'ly unfavourable inconnection t high-frequency understood and readily carried into effect,it will heati hi i t he used for depriving t now be explained more fullywith reference to tube parts of gases, for the very reason that they theaccompanying drawing in W ch Fig. 1 is a have such a low specificresistance. Just in conperspective w Of an n e element in accorde ii itt high-frequency heating metals ance with the invention and Fig. 2 is aschematic like nickei and i have very favourable eiecview of an electricdischarge tube in which is used tric resistance and the magnetic lossesof these the anode of F metals are also high. Owing to these differentlyA plate-like element f iron which is to be directed properties, metalslike copper, silver and. used as the anode and Whose thickness is 125the like would have to be used in connection with microns is coated Witha Copper layer m 10 to one of t properties rather t nickel iron or 15microns thick before being housed in the tube. the like, but inconnection with other properties This coating y be effected in lwn manitwould be necessary to do the very reverse. her, for example t y ly or bycata- Now, these difliculties may be obviated by the phel'etie yeXt theelectrode thus 0buse of an electric discharge tube according to thetamed is assembled W the Other ube parts in present invention containingone or more electhe normal manner and the u s then fintrodes or otherconductive parts built up from a dbase of nickel, iron, nickel-iron orsimilar mate- In a furth r f rm of construction an iron wire rials whichhas applied to it a layer of copper, having a thickness of 250' micronsand being suitsilver or other materials of similar conductivity able toact as a connecting element between an whose thickness is from 15 to 30microns. electrode and a current supply conductor is coated In adischarge tube according to the invention with a silver layer of from 10to 15 microns. Such silver coating is preferably applied to thoseelements which are liable to oxydation, for example are arranged in theproximity of a seal, but which on the other hand are not overheated inthe case of high-frequency heating or while the tube is in use.

What we claim is:

1. A high frequency electric discharge tube comprising an envelope andan electrode system within said envelope comprising a metallic body themajor portion of which is selected from the group nickel, iron andcobalt, said body being plated to a thickness of from about 10 to about30 microns with a metal of high electrical conductivity.

2. A high frequency electric discharge tube comprising an envelope, andan electrode system within said envelope comprising an electrode havinga metallic body the major portion of which is selected from the groupnickel, iron and cobalt, said body being plated to a thickness of fromabout 10 to about 15 microns with copper.

FRITS PRAKKE. WILLEM KEEMAN. IQ'AAS RODENHUIS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,543,033 Snelling June 23, 19251 1,872,359 Sutherlin Aug. 16, 1932 1,877,204 Smalley Sept. 13, 1932

